The invention relates to a hydraulic axial piston machine, having a inclined plate, on which a slider shoe of at least one piston slides on relative movement between a cylinder body receiving the piston and the inclined plate, and a pressure plate articulated on the cylinder body and holding the slider shoe in engagement with the inclined plate.
In machines of that kind, on rotation of the cylinder body with respect to the inclined plate, or on rotation of the inclined plate with respect to the cylinder body, the piston is moved axially. During the pressure stroke, that is to say, on decrease in the volume of the cylinder moved by the piston, the inclined plate exerts a pressure on the slider shoe. During a suction stroke, on the other hand, the pressure plate has to hold the slider shoe in engagement with the inclined plate. In accordance with the axial back and forth movements of the piston, the pressure plate must also tilt back and forth, the tilting angle range extending, for example, from about -15.degree. to about +15.degree.. On each rotation, the entire tilting angle range has to be passed through, once in the positive direction and once in the negative direction.
Since the articulated connection between the cylinder body and the pressure plate has to accommodate considerable forces, considerable friction is generated there. So that the losses and the wear and tear caused by the friction are not allowed to become too great, it is known to lubricate this articulation. The oil that is already present, serving as hydraulic fluid, is normally used for that purpose. But this leads to the disadvantage that the selection of hydraulic fluids is restricted to hydraulic oils. Even here, choice is not unlimited since not all oils have the same good lubricating properties. In the past, there has therefore been an increasing tendency to use synthetic oils, but these are being regarded with growing disfavour from the point of view of compatibility with the environment.